[llvm] [RemoveDIs] Load into new debug info format by default in LLVM (PR #89799)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

> we're seeing a stage 2 ThinLTO (+PGO) build of clang failing with the above verifier error, any ideas what this could be?

Not immediately clear: the second error is a verifier error resulting from a bad `!DISubprogram` attachment to a function, which in theory shouldn't be _directly_ impacted by this change, since this is only concerned with debug intrinsics/records, not with debug metadata attachments to non-debug objects. The first error looks entirely unrelated, I've no clear idea how this change could result in changing the linkage of a symbol - at the very least it sounds like it would be a "debug affecting codegen" error if true?

I've only got vague suspicions from those error messages - are you able to share anything else? Reduced reproducers are obviously best, but if those aren't immediately available then it would help to know what flags were used, and at what point in compilation the error is occurring at: is this during pre-link optimization pipeline, immediately after loading bitcode for linking, immediately after linking (I suspect it's probably this), or during/after the post-link optimization pipeline?

https://github.com/llvm/llvm-project/pull/89799